Kanankege Kaushi S T, Traynor Isaac, Perez Andres M
Center for Animal Health and Food Safety, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, United States.
School of Public Health, University of Minnesota, Minneapolis, MN, United States.
Front Vet Sci. 2023 Feb 8;9:1052306. doi: 10.3389/fvets.2022.1052306. eCollection 2022.
A 2018 publication reported that communities living near hog Concentrated Animal Feeding Operations (CAFO) in North Carolina, USA have increased negative health outcomes and mortalities. While the authors stated that the associations do not imply causation, speculative interpretation of their results by media and subsequent use as evidence in lawsuits caused detrimental effects on the swine industry. We repeated their study using updated data to evaluate the strength of conclusions and appropriateness of methods used with the ultimate goal of alerting on the impact that study limitations may have when used as evidence. As done in the 2018 study, logistic regression was conducted at the individual level using 2007-2018 data, while presumably correcting for six confounders drawn from zip code or county-level databases. Exposure to CAFOs was defined by categorizing zip codes into three by swine density; where, >1 hogs/km (G1), > 232 hogs/km (G2), and no hogs (Control). Association with CAFO exposure resulting in mortality, hospital admissions, and emergency department visits were analyzed related to eight conditions (six from the previous study: anemia, kidney disease, infectious diseases, tuberculosis, low birth weight, and we added HIV and diabetes). Re-evaluation identified shortcomings including ecological fallacy, residual confounding, inconsistency of associations, and overestimation of exposure. HIV and diabetes, which are not causally relatable to CAFOs, were also prominent in these neighborhoods likely reflecting underlying systemic health disparities. Hence, we emphasize the need for improved exposure analysis and the importance of responsible interpretation of ecological studies that affect both public health and agriculture.
2018年的一项研究报告称，美国北卡罗来纳州生活在生猪集中式动物饲养场（CAFO）附近的社区出现负面健康结果和死亡率上升的情况。虽然作者表示这些关联并不意味着存在因果关系，但媒体对其研究结果的推测性解读以及随后在诉讼中用作证据的做法，对养猪业造成了不利影响。我们使用更新后的数据重复了他们的研究，以评估结论的可信度和所用方法的适当性，最终目的是提醒人们注意研究局限性用作证据时可能产生的影响。正如2018年的研究所做的那样，我们使用2007 - 2018年的数据在个体层面进行了逻辑回归分析，同时可能对从邮政编码或县级数据库中提取的六个混杂因素进行了校正。通过将邮政编码按生猪密度分为三类来定义接触CAFO的情况：每平方公里>1头猪（G1）、每平方公里>232头猪（G2）以及无猪（对照）。分析了与CAFO接触导致的死亡率、住院率和急诊就诊率与八种疾病的关联（六种来自之前的研究：贫血、肾病、传染病、结核病、低出生体重，我们还增加了艾滋病毒和糖尿病）。重新评估发现了一些不足之处，包括生态谬误、残余混杂、关联不一致以及接触估计过高。艾滋病毒和糖尿病与CAFO并无因果关系，但在这些社区也很突出，这可能反映了潜在的系统性健康差异。因此，我们强调需要改进接触分析，以及负责任地解读影响公共卫生和农业的生态研究的重要性。
